Copper dendrite growth and analysis on copper damascene process

Chemical mechanical polishing (CMP) process has been used for dielectric planarization, and contact and via formation in aluminum (Al)-tungsten (W) metallization. However, more challenges are encountered when it is used in copper (Cu) damascene process because copper is very easily corroded in a wet environment and its oxidation is not self-limiting like Al. Some new and unique defects would be introduced during copper CMP process. These would contribute to the defect density for the present or even the next few layers and ultimately influence the final yield of the wafer. In this paper, a very unusual defect, copper dendrite, which is due to the CMP process, would be discussed.